Without knowing who your service provider is, or whether you have your own domain name, it's difficult to answer.

I'd guess the bit that is dissimilar is before the '@'...

If you are a Freeserve (UK) user, then your email address could have anything at all before the '@', as your username is the bit after the '@'... example: freddy@bloggs.fsnet.co.uk may be the email address you registered, but sausage@bloggs.fsnet.co.uk will also get through. It's a similar situation if you own your domain name.

The simplest solution is to set up 'rules' in your email client, be it Outlook, Outlook Express or whatever, which filters out mail not sent to your 'real' eamil address and puts it into a 'spam' folder for deletion later. You could even send it straight to the deleted items folder, though that may not be wise.

Zone Alarm itself may well have such a facility... I don't know, having never used it.